The present invention relates to a shifting claw transmission including an electric motor, particularly for a motor vehicle, and to a shifting method for shifting a shifting claw transmission of a motor vehicle.
U.S. Pat. No. 5,560,249 discloses a group transmission with claw clutches in which a power synchronizer which comprises an electric motor is used. The electric motor drives a countershaft via an intermediate gearwheel.
In addition, DE 42 020 83 C2, which is of a different generic type, discloses, for a hybrid vehicle, a vehicle transmission which has a frictionally locking synchronization means and an electric machine dynamo. The dynamo electric machine can be operatively connected to a countershaft so that the latter can be used as synchronization means for relieving the loading on the frictionally locking synchronization means.
EP 1007383 B1 discloses a drive train for a hybrid vehicle including a dynamo-electric machine mounted to a countershaft.
DE 195 30 231 discloses a hybrid drive for a motor vehicle in which an internal combustion engine and an electric motor are used as the drive. The internal combustion engine and the electric motor act simultaneously or alternately on the drive shaft or the countershaft of a speed-changing transmission which is provided with shiftable gearwheels and with synchronous clutches for shifting a plurality of gear speeds. In order to achieve comfortable gear speed changes, the electric motor can be coupled to the drive shaft via a positively locking clutch. This clutch is released when a gear speed is engaged and subsequently closed again. Before the clutch closes, the electric motor is adjusted at least approximately to synchronous running in relation to the drive shaft.
An electric motor with a speed change transmission is also known from DE 198 59 458 A1, which is of a different generic type.
DE 10224357 A1 discloses a shifting element, in which a spring is provided so that, in the event that the shifting claw clutch is in a tooth-to-tooth position, no components are deformed during shifting.
EP 0 873 902 B1 discloses a shifting method for a shifting claw transmission, in which a rotational speed difference between the components to be engaged is ensured in order to facilitate shifting of the shifting claw clutch.
It is the object of the present invention to provide a reliable utility vehicle transmission permitting automatic shifting of gears with a shifting claw transmissions and a method of operating such a transmission.